A typical measuring transducer without the disclosed improvements of the present invention is illustrated in SIEMENS Catalogue MP 17, 1999 and is referred to as SITRANS P DS. The measuring transducer disclosed in this catalogue has a pressure sensor with a sensor signal that is amplified, digitized and subsequently evaluated in a microcontroller and adjusted with respect to linearity and temperature behavior. The measuring signal thus processed is supplied via a data interface, e.g., PROFIBUS or HART, to the communications system of a technical plant in which the measuring transducer is installed. The measuring transducer also can be parameterized via the data interface, for instance from a plant control room, etc.
In larger technical plants, thousands of measuring transducers may be installed, each detecting a single parameter value, such as pressure, temperature, etc., that must be recorded and processed accurately to ensure proper operation of the plant. To start up or maintain such a plant, every connection path, for instance from the plant control room to the many individual measuring points, must be checked. Furthermore, the functionality of all the partial areas as well as of the entire system must be checked when the system is initially started. In the aggregate, the length of communication line needed comprises several hundred meters between each of the measuring points and the plant control room. This results in several kilometers of line length, each of which must be tested and maintained often (initially, at plant startup, as well as periodically) to ensure proper parameterization of the system operation within the plant.
However, since there are typically no actual, or “real”, measured values available during this testing or maintenance, conventionally, parameter values have been digitally simulated within the control system of the plant. To accommodate this simulation much storage space and program runtime had to be kept available in the individual components of the control system. Additionally, the effects of the long distances between the measuring points and the plant control room were excluded from the simulation and had to be taken into account by other means.
To initiate a measuring transducer without real measured values being available, one conventional solution utilizes a dummy sensor, for instance in the form of a resistor network connected to the electronics of the measuring transducer. The dummy sensor can be adjusted to provide different resistance values and, thus, can supply a simulated signal to the plant control room that can be used for test purposes. This technique, however, involves substantial mechanical complexity and requires qualified personnel at each of the individual measuring points.